Analysis of room-temperature bonded compliant bump with ultrasonic bonding

Keiichiro Iwanabe, Takanori Shuto, Tanemasa Asano

Research output: Chapter in Book/Report/Conference proceedingConference contribution

6 Citations (Scopus)


Room temperature microjoining of Au or Cu bumps in the air ambient has been achieved by bonding cone-shaped microbumps with ultrasonic application. This technology has been applied to fabrication of near infrared (NIR) image sensor of q-VGA (quarter video graphic array) resolution, where InGaAs/InP phtosensor array is joined with CMOS read out in the pixel level and, therefore, low temperature bonding is strongly required to address problems caused by mismatch in thermal expansion of the two materials. In this work, we investigate bonding mechanism of the cone shaped microbump using bumps made of Au. Die shear tests shows that shear strength of the bonded chips is proportional to the bonded contact area of the bump and that room temperature bonding gives sufficient bonding strength for applications while bonding at elevated temperature results in higher bonding strength. Analysis of change in bump height shows that 'softening' of Au bump takes place under the application of ultrasonic vibration. Transmission electron microscopy shows that crystal grains at the bonded interface transform to small crystallites.

Original languageEnglish
Title of host publicationProceedings - Electronic Components and Technology Conference
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages5
ISBN (Electronic)9781479924073
Publication statusPublished - Sep 11 2014
Event64th Electronic Components and Technology Conference, ECTC 2014 - Orlando, United States
Duration: May 27 2014May 30 2014


Other64th Electronic Components and Technology Conference, ECTC 2014
Country/TerritoryUnited States

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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